It has been announced during the 2012 Cannes Film Festival that the 'Byzantium' actress is sealed to lead the period drama adapted from Brittain's heartbreaking World War I memoir.

Photo credit: Lia Toby/WENN

Saoirse Ronan is set to get back to her period drama roots. After nabbing a role in sci-fi film "The Host (2013)", the 18-year-old actress secures the lead in "Testament of Youth", a movie project based on a heartbreaking World War I memoir about British pacifist Vera Brittain.

The casting was announced during the 2012 Cannes Film Festival by BBC Films, which is set to finance the movie project. Serving as the producer is David Heyman, who also produced the "Harry Potter" film series.

Ronan will tackle the part of Brittain, who is a disillusioned nurse during the war. The story will take place during the beginning of her career as a journalist and pacifist. Adapting the story from Brittain's 1933 best-selling memoir is scribe Juliette Towhidi.

In addition to "Testament of Youth", BBC Films announced its other project at Cannes. The studio confirmed its reunion with "My Week with Marilyn" director Simon Curtis to develop a new drama pic called "The Golden Lady".

"The Golden Lady" will be written by playwright Alexi Kaye Campbell with David Thompson serving as the producer. The film will center on Maria Altmann, a refugee from Nazi Austria who who waged a campaign to reclaim Klimt paintings that had been stolen by the Nazis.